1. Field of the Invention
The present invention relates generally to the art of data bitstream encoding and decoding, and more specifically to updating sequences within a bitstream.
2. Description of the Related Art
Users access the Internet today using various devices capable of delivering content in a variety of formats. Faced with variations in the type of content that may be transmitted or received from a user, a rigid media representation format, producing decompressed content only at a fixed resolution and quality, presents various limitations. Certain users may not have the ability to receive any content, or may receive poor quality and/or resolution data considering the capabilities of their network connections and/or accessing devices. The inability to provide content in formats compatible with new devices has had a tendency to inhibit the growth of new rich media and the devices on which they are used, because such rich content can be used only to high end devices.
One known technique for providing media content to users having a variety of capabilities and preferences is to provide multiple versions of the media suiting a variety of capabilities and preferences. While this approach works with delivery models where the recipient directly connects to the media originator, for any other scenario, significant redundancy and inefficiency may be introduced, leading to wastage of bandwidth and storage. Redundancies and inefficiencies are particularly problematic when providing a wide range of choices catering to a large consumer base, thereby mandating maintenance of numerous versions differing in a variety of ways.
To combat these redundancies and inefficiencies, scalable compression formats have been proposed. Scalable compressed representations can accommodate all users by automatically addressing a given user's computing power and connection speed. One example of a scalable compressed representation is JPEG2000. JPEG2000 is a scalable standard for still images that seeks to combine image quality scalability and image resolution scalability in a format specific to the universal JPEG2000 compressed data, enabling distribution and viewing of images of various qualities and resolutions using various connections and devices. To obtain the full benefits of JPEG2000 format scalability, an infrastructure that specifically supports transcoding of JPEG2000 content and delivery to a heterogeneous recipient base is required.
Video standards MPEG-X and H.26X have been developed that incorporate various forms of scalability for delivering media content such as streaming video to a heterogeneous recipient base. However, this type of scalable video over the Internet is limited to maintaining multiple versions for a few different types of connections, because complete infrastructures that support transport of scalable video formats are nonexistent.
Various types of bitstream scalability can be devised depending on the type of media content addressed. For example, SNR (quality) scalability refers to progressively increasing quality as more and more of the bitstream is included, and applies to most types of media. Resolution scalability refers to fineness of spatial data sampling, and applies to visual media such as images, video, 3D etc. Temporal scalability refers to fineness of sampling in the time-domain, and applies to video and other image sequences. Certain scalability pertains solely to audio, such as number of channels and sampling frequency. Different types of scalability can co-exist, so as to provide a range of adaptation choices.
In new rich media, different media elements are often bundled together to provide a composite media experience. According to one known technology, an image with audio annotation and some animation provides a composite experience of a presentation using three media elements (an image, an audio clip, some animation data). Composite rich media models such as this lead to newer types of scalability specific to the media, because certain non-critical elements of the composite may be dropped to accommodate other more critical ones within the limited resources of a recipient.
Security is an added critical factor to content deployment. Full end-to-end security may only be available using delivery architectures where no codec-specific elements are used in the entire path from, and perhaps including, the content server to the receiving terminal. Any point in the network using a codec-specific element presents a potential security breach point.
In both unsecured and secured transmission scenarios, midstream content adaptation to cater to diversity is desirable, i.e. the ability to alter data at a midpoint between transmission and receipt. Data that may be altered may include various portions of the bitstream, including but not limited to data fields, data sequences, and the like. Currently, secure end-to-end streaming using scalable packets exists. However, to enable secure content adaptation in a content-agnostic manner, it is necessary to enable network adaptation engines to make decisions about possible adaptations, even when the adaptations do not have all information regarding the semantics of the required decision.
With respect to data sequences, after altering or adapting the bitstream in midstream, sequence count fields may point to dropped data, i.e. data no longer available. Decoding and updating the sequence fields may present a significant undertaking from a resource and timing viewpoint and be undesirable.
Based on the foregoing, it would be advantageous to offer a system and method of bitstream transmission capable of performing decision making tasks in a relatively compact way using a content-agnostic mathematical abstraction in generic descriptors readily able to be processed by a device such as an adaptation engine. Further, a system that enables updating of bitstreams, including but not limited to sequence fields, without decoding the bitstream may provide advantages over previous designs.